<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }

        p{
            background: pink;
        }

        .Test2{
            background: skyblue;
        }

        #Test3{
            background:gold;
        }
    </style>
</head>
<body>
    <p>测试案例1</p>
    <div class = "Test2">测试案例2</div>
    <div id = "Test3">测试案例3</div>
</body>
</html>